BAGHDAD — The U.S. military faced complaints Tuesday from its Sunni allies over claims that more civilians had been killed by American forces — amplifying tensions as the Pentagon tries to calm anger over an airstrike last week that claimed innocent lives.

The disputes have further strained ties with anti-al-Qaida fighters considered crucial in turning the tide against extremist violence.

The latest deaths occurred when U.S. soldiers — acting on tips — stormed a squat, mud-brick house in the village of Adwar, 10 miles south of Saddam Hussein's hometown of Tikrit. The predominantly Sunni area is home to many former members of Saddam's regime.

The U.S. military said a gunbattle broke out after the troops came under small-arms fire by two suspected terrorists. It acknowledged a woman was killed and a child was wounded, but said it was not clear who shot them. Two other men — described as insurgents — were killed.

But Iraqi police, relatives and neighbors said a couple and their 19-year-old son were shot to death in their beds. Iraqi police also said two girls were wounded and one later died.

It was the second time in as many days that the U.S. military conceded involvement in the death of Iraqi civilians. On Monday, the military said it had accidentally killed nine Iraqi civilians.

The killings illustrate the increasing difficulty in identifying the enemy as the nature of the U.S.-led war in Iraq has changed. Many former insurgents and tribal leaders have joined forces with the Americans against al-Qaida in Iraq. The mistaken shootings also threaten to jeopardize the fragile relationship between the Americans and their new Sunni partners.

Both U.S. raids on Saturday and Tuesday were based on what the military said was intelligence gleaned from informants. That raised the possibility that the military was misled into targeting the households, perhaps as part of an insurgent campaign to derail the U.S.-backed Sunni revolt against al-Qaida in Iraq..

"I cannot rule out that the enemy is trying to sow seeds of division between us and the Americans," Col. Mutasim Ahmed, head of Adwar's Awakening Council, said.